Question 1

How fast is rapidhash compared to xxh3?

Accepted Answer

Rapidhash often outperforms xxh3 in throughput, e.g., 71GB/s vs 49GB/s on M4, but xxh3 can be faster on some CPUs like Ryzen 9700X. Both are high-quality, but rapidhash avoids hardware-specific instructions for platform independence.

Question 2

How to use rapidhash in a C++ project for hash tables?

Accepted Answer

Download the header-only files from GitHub and include them; the functions are simple to call like standard hashes. For best performance, enable the RAPIDHASH_UNROLLED macro for long inputs, as noted in the benchmarking section.

Question 3

Is rapidhash secure for passwords or cryptographic use?

Accepted Answer

No, rapidhash is explicitly non-cryptographic and not designed for security. It lacks properties like pre-image resistance, so use dedicated cryptographic hashes like Argon2 or SHA-256 for passwords.

Question 4

What's the difference between rapidhash, rapidhashMicro, and rapidhashNano?

Accepted Answer

Rapidhash is general-purpose with balanced performance, rapidhashMicro optimizes for cache efficiency in server apps, and rapidhashNano minimizes code size for embedded systems. They produce identical outputs for small inputs up to 48 or 80 bytes.

Question 5

Can rapidhash be used in embedded systems with memory constraints?

Accepted Answer

Yes, rapidhashNano is designed for this, compiling to less than 100 instructions with no stack usage. However, it's slower for larger inputs, so profile based on your typical data sizes.

Question 6

Does rapidhash support seeding for different hash outputs?

Accepted Answer

Yes, the README mentions using a default seed of 0 in experiments, implying seed support. For varied outputs, you can likely modify the seed parameter similar to other non-cryptographic hashes.

Question 7

How to port rapidhash to another language like Python?

Accepted Answer

Reference existing ports to Java, Rust, JavaScript, and Go for guidance. The C implementation is straightforward, but ensure to replicate the algorithm exactly to maintain quality and performance, as the README emphasizes platform independence.

rapidhash

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